The use of the interferon system in ascertaining interactions among polynucleotides will be extended to guanosine containing polymers and xanthosine polymers as well as to DNA triplexes and DNA-RNA hybrid triplexes with the goal of determining the kinds of triplexes that might reasonably be expected to exist in nature. The synthesis of a number of new modified nucleosides will be undertaken in order to evaluate their potential as antiviral and antineoplastic agents and, after polymerization to polynucleotide, their physicochemical and interferon-inducing characteristics. In addition, the immunochemistry and reverse transcriptase inhibiting properties of such polymers will be explored.